This invention relates to an optical assembly for use in a barcode reader and, in particular, to an adjustable apparatus for positioning a sharp line of illuminator in barcode space image of a barcode target at the.
Although the advantages associated with light emitting diodes (LEDs) when used in barcode scanning equipment are well known, the level of the intensity produced by this type of lamp is relatively low when compared to other light sources, such as halogen lamps or arc lamps. In an effort to improve the effectiveness of light emitting diodes in this application, it is sometimes customary to employ a relatively large number of lamps aligned in one or more rows above or below the imaging lens. As a result, the target region, as well as the periphery of the target region, are flooded with excessive light energy. This approach, however, is space consuming and poses certain assembly and alignment problems.
Optical units have also been devised for providing coplanar illumination wherein the light emitting diodes are mounted in the same plane as the imager on both sides of the imaging lens. Light from the light-emitting diodes is further passed through magnifying lens to project the light onto the barcode target. Additionally, diffusers are used in association with the LEDs to more uniformly distribute the light within the target area. Here again, these optical units overcome many of the problems associated with LED illumination systems. They nevertheless pose certain other problems relating to bringing the components together in assembly to provide compact, easy to install and adjust units suitable for use in a hand-held long range scanner.